Kitties using flowerbeds...I found that by planting a catnip plant in the edge of my garden, where they could roll on it and not disturb any of my seeds or plants, that they stopped using it for a litter box. It has to do with not going to the bathroom where you eat. They left all of my garden plots alone after they found the catnip. This will be season two, and my house cat is thrilled to get fresh catnip from time to time as well. Hope it helps.
Nikki